Methods, systems, and devices for measuring in situ saturations of petroleum and NAPL in soils

ABSTRACT

Improved devices, systems and methods for measuring in situ saturations of non-aqueous phase liquids and/or petroleum in media such as soil. A clear or otherwise UV-transparent well for detecting fluorescence in a soil column having a transparent casing and an oil sensing device positioned in the well configured to monitor the soil column. A method for real-time estimation of LNAPL saturations in media, including emplacing a UV-transparent well in the media and recording fluorescence in the media via an oil sensing device.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.16/047,491, filed Jul. 27, 2018, entitled “Method, Systems, and Devicesfor Measuring In Situ Saturations of Petroleum and NAPL in Soils,” whichclaims priority to U.S. Provisional Application No. 62/537,682 filedJul. 27, 2017, each of which are hereby incorporated by reference intheir entirety.

TECHNICAL FIELD

The disclosed technology relates generally to improved devices, systemsand methods for measuring in situ saturations of non-aqueous phaseliquids and/or petroleum in media such as soil.

BACKGROUND OF THE INVENTION

In situ monitoring of petroleum in soils is done using two commonly usedtechniques. One is direct sensing of petroleum thickness in wells withan oil-water interface probe (OWIP). In this method, a sensor attachedto a tape measure is lowered into the petroleum-containing well. Thesensor indicates (typically by emitting a beeping sound) when it reachesthe air-petroleum and the petroleum-water interfaces.

Another in situ petroleum monitoring technique is a one-time surveyusing laser induced fluorescence (LIF). This technique uses a LIF sensormounted to a drill probe. The LIF probe shines a UV laser and detectsthe fluorescence response of the petroleum hydrocarbon in the soil theprobe penetrates. This technique was developed by the US Army Core ofEngineers and was patented in the early-mid 1990s. The technique iscurrently commercialized by Dakota Technologies, Inc. (DTI) and the LIFone-time survey equipment are available therefrom. At least two othercommercial enterprises hold licenses from DTI: Matrix and ColumbiaTechnologies.

The disadvantage of the OWIP method is that the well itself acts as thelargest pore in the ground, and tends to accumulate much more petroleumthan the geologic formation, thus resulting in an inaccuratemeasurement. FIG. 1 shows the results of a sand tank experiment in whicha simulated well (against the sand tank glass window) show both thepetroleum thickness in the well and the petroleum in the formation. Inthis experiment, the petroleum is diesel with a small concentration offluorescent dye tracer. There is a large difference between thepetroleum well thickness (what the OWIP method would sense) and theactual distribution in the formation. The petroleum in the well does notreflect the immobile LNAPL below the water table (surrounded by water),nor the residual saturations in the vadose zone (the mostly air-filledpart of the soil column above the water table). Additional effects suchas heterogeneities in the soil can exacerbate these differences. Forexample, petroleum confined between fine lenses of fine pore materials,such as clay, can show up in wells even though there is none in theformation at the water table.

LIF is an widely used method tested by the EPA's Technology VerificationProgram. The limitation of LIF is that it requires drilling with everymeasuring event. The implications are that it is a destructive method(each bore hole can only be used once) and that it requires largeequipment and personnel mobilization efforts associated with every eventof drilling and sampling. It can be coupled with other high resolutionmeasurements, with the associated devices attached to the drillingequipment point (such as, for example, a hydraulic profiling tool ormembrane interface probe). FIG. 2 shows a schematic diagram of theequipment used (http://www.columbiatechnologies.com/services/#HRVP)

There is a need in the art for an improved method, system, and devicefor measuring in situ saturations of petroleum and non-aqueous phaseliquid (NAPL) in soils.

BRIEF SUMMARY

Discussed herein are various devices, systems, and methods relating tomeasuring in situ saturations of non-aqueous phase liquids and/orpetroleum in media such as soil.

In one Example, a system of one or more computers can be configured toperform particular operations or actions by virtue of having software,firmware, hardware, or a combination of them installed on the systemthat in operation causes or cause the system to perform the actions. Oneor more computer programs can be configured to perform particularoperations or actions by virtue of including instructions that, whenexecuted by data processing apparatus, cause the apparatus to performthe actions. One general aspect includes a UV-transparent well fordetecting fluorescence in a soil column, including a casing including atransparent window; and an oil sensing device positioned in the wellconfigured to monitor the soil column. Other embodiments of this aspectinclude corresponding computer systems, apparatus, and computer programsrecorded on one or more computer storage devices, each configured toperform the actions of the methods.

Implementations may include one or more of the following features. Thewell further including a UV light source. The well further including anoil sensing device. The well where the oil sensing device is afluorescence sensing device. The well where the oil sensing device is aUV camera. The well where the oil sensing device is a fiber optic devicein operable communication with a spectrometer. The well where the oilsensing device is a laser-induced fluorescence device. Implementationsof the described techniques may include hardware, a method or process,or computer software on a computer-accessible medium.

One Example aspect includes a UV-transparent well for detectingfluorescence in a soil column, including: a UV-transparent well, a UVlight source; and a fluorescence sensing device. Other embodiments ofthis aspect include corresponding computer systems, apparatus, andcomputer programs recorded on one or more computer storage devices, eachconfigured to perform the actions of the methods.

Implementations may include one or more of the following features. Thewell further including a fiber optic optical device configured totransmit and receive UV light to and from the source to the soil column.The well further including a computer configured to perform abinarization algorithm. The well where the computer is configured toevaluate in situ soil saturations. Implementations of the describedtechniques may include hardware, a method or process, or computersoftware on a computer-accessible medium.

One Example includes a method for real-time estimation of LNAPLsaturations in media, including: emplacing a UV-transparent well in themedia; and recording fluorescence in the media via an oil sensingdevice. Other embodiments of this aspect include corresponding computersystems, apparatus, and computer programs recorded on one or morecomputer storage devices, each configured to perform the actions of themethods.

Implementations may include one or more of the following features. Themethod where the UV-transparent well is emplaced in a soil column. Themethod further including generating fluorescence in at least oneformation associated to contaminants by exposing the media to a UVlight. The method where the recording florescence includes capturingimages of the fluorescence using a miniature digital camera and/or aspectrometer. The method further including processing captured digitalimages of the fluorescence to establish the location of contaminant. Themethod further including quantifying soil pore contamination saturationvia digital imaging binarization. Implementations of the describedtechniques may include hardware, a method or process, or computersoftware on a computer-accessible medium.

While multiple embodiments are disclosed, still other embodiments of thedisclosure will become apparent to those skilled in the art from thefollowing detailed description, which shows and describes illustrativeembodiments of the disclosed apparatus, systems, and methods. As will berealized, the disclosed apparatus, systems, and methods are capable ofmodifications in various obvious aspects, all without departing from thespirit and scope of the disclosure. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 is a cutaway side view of a petroleum visualization experiment ina sand tank (with a glass window) showing petroleum distribution in thewell and the formation. Petroleum hydrocarbon (diesel) is dyed with afluorescent dye and shows with a bright yellow color under UV light.

FIG. 2 is a schematic view of a typical configuration of a high densitysurvey (including LIF).

FIG. 3 is an Illustration of use of the disclosed in situ well,according to one embodiment (right) next to a traditional monitoringwell (left).

FIG. 4 is a cutaway side view depicting how well construction affectsmeasurement next to well boring.

FIGS. 5A-E are an example LIF report from Columbia Technologies, whereLIF intensity is shown as a function of depth in soil.

FIG. 5A shows hydraulic profiling tool results (relative permeability).

FIG. 5B shows the blue LIF signal (relative fluorescence, blue signal).

FIG. 5C shows the red LIF signal (relative fluorescence, red signal).

FIG. 5D shows the green LIF signal (relative fluorescence, greensignal).

FIG. 5E shows temperature (° C.).

FIGS. 6A-6C depict the processing of the digital images to determine oilsaturations in the soil, according to certain embodiments.

FIG. 6A is an original digital image adjusted to binarize it (whitepixels indicate fluorescence and NAPL presence, while black ones reflectthe lack of it).

FIG. 6B is a binary picture processed by averaging values across eachelevation (values of 1 for white, 0 for black).

FIG. 6C is a chart depicted average NAPL saturations at each elevation.

FIG. 7 is a cross-sectional view of an exemplary embodiment of a fiberoptic probe, according to one implementation.

FIG. 8 shows the excitation signal as recorded by spectrometer (incombination with a fiber optic assembly as in FIG. 5).

FIG. 9A depicts a side views of a simulated well. The simulatedcontaminant appears as bright yellow, and only does so when excited byUV light.

FIG. 9B depicts an endlong view of a simulated well. The simulatedcontaminant appears bright yellow, and only does so when excited by UVlight.

FIG. 9C depicts a side view of a simulated well. The simulatedcontaminant appears as bright yellow, and only does so when excited byUV light.

FIG. 10A shows the saturated contaminant (LNAPL) thickness of the imageof FIG. 9A.

FIG. 10B shows the saturated contaminant (LNAPL) thickness of the imageof FIG. 9B.

FIG. 10C shows the saturated contaminant (LNAPL) thickness of the imageof FIG. 9C.

FIG. 11A is a close-up photograph within UV transparent well of FIG. 9.

FIG. 11B is a binarized rendering of FIG. 11A, showing contamination inwhite.

FIG. 11C is a saturation average for the binarized rendering of FIG.11B.

FIG. 11D depicts the example simulated well used in FIGS. 11A-11C.

DETAILED DESCRIPTION

The various embodiments disclosed or contemplated herein relate tomethods, systems, and devices for detecting fluorescence of petroleum insoils though a UV transparent material, instead of traditional wellmaterials such as PVC pipe (typically slotted or screened at discreteintervals or entirely).

In accordance with certain implementations, the device for detectingfluorescence of petroleum is a UV-transparent well casing that enablesdirect detection and measurement of LNAPL through the well in anon-destructive manner. The various embodiments include the well casingbeing used in combination with an oil sensing device positioned therein.

FIG. 3 depicts one embodiment of a UV-transparent well casing 10 forminga dry well 12. A traditional well 11 is also depicted. In thisembodiment, the well 12 is dry because the casing 10 is not slotted andis sealed or “plugged” at the bottom so that external fluids do notdrain into the well 12. In this configuration, the UV-transparent wellcasing 10 can be used as a transparent window into the ground by whichan oil sensing device 14 positioned in the well 12 can monitor any pointin the soil column (above and below the water saturation level).

In this embodiment, a combination of ambient natural light 13A and a UVlight source 13 disposed within the well 12 illuminate theUV-transparent well casing 10. A sensing device 14 (in this case adigital camera) is disposed within the well 12 so as to detect thefluorescence 15 of the petroleum or NAPL. The sensing device 14 is inoperational communication with a computer or other display device (notshown) and is thereby able to generate an image 16 of the fluorescence15, which is shown schematically in FIG. 3. It is understood that suchan image 16 is displayed on the computer or display device 17). It isfurther understood that the use of natural light in combination with theUV light enables the visualization of additional soil features such asgrain size, colors, and the like.

An additional advantage of the sealed well casing 10 is that thedistribution of fluids in the soil adjacent to the casing 10 will not beinfluenced by the well itself (as would be the case in a typical wellinstallation). The sealed well casing 10 ensures that the well 12 is nothydraulically connected to the formation, thereby avoiding the high biascaused by the well acting as both the largest pore in the formation andas a point of zero pressure (hydraulically connected to the ambientair). Thus, the sealed casing 10 results in LNAPL saturations morerepresentative of the formation when the saturations are sensed throughthe casing 10 by fluorescence methods.

In one alternative, the well casing 10 is not sealed or plugged.

In one embodiment, the method of placing the well casing 10 includes notadding any external materials to fill in any portions of the holeremaining from the drilling of the well. As shown in FIG. 4, a typicalwell is constructed by drilling a hole, and while the hollow drillingstem is in the ground, a well casing is positioned in the hole. The voidaround the well casing created by the hole can be filled in using one oftwo different standard techniques: (1) adding external materials(typically coarse sand), or (2) allowing the native formation tocollapse while the drilling stem is removed.

The addition of external materials, which is depicted in FIG. 4, wouldcause inaccurate measurements using the methods, systems, and devicesdisclosed herein. That is, the accuracy of the fluorescence measurementsis dependent on monitoring soils as similar to the natural formation aspossible, and the use of external materials would significantly alterthe natural formation. Thus, certain embodiments of the method disclosedherein include allowing the native formation to collapse while thedrilling stem is removed.

According to another embodiment, the method can also include freezingthe ground in place prior to drilling (to minimize soil and petroleumdisturbance). CSU is currently working on such a technology. That is,CSU is pursuing in situ soil characterization by nuclear magneticresonance (“NMR”) in combination with freeze drilling to preserve thepart of the formation below groundwater while drilling.

Returning to FIG. 3, the sensing device 14 can be a device that sensesthe presence of petroleum upon excitation by UV light source 13 andphotography (upon exposure to UV light), spectrometry (such as a fiberoptic device, such as a cable, connected to a spectrometer), orlaser-induced fluorescence (such as a LIF probe). Alternatively, anyknown oil sensing technology, such as, for example, any optically-basedoil sensing technology, can be utilized.

The various UV transparent materials that can be used in the variouswell casing implementations herein include clear PVC, polymethyl pentene(“PMP”), UV transparent acrylic, and glass. In certain embodiments, theclear PVC or the UV transparent acrylic can be special or uniqueformulations. In one specific example, the UV transparent acrylic iscommercially available from Ridout Plastics.

As mentioned above, certain devices and methods disclosed andcontemplated herein utilize fluorescence to determine the amount ofpetroleum in the solid. Fluorescence consists of excitation with UVlight (non-visible), which generates emission of light (typically in thevisible range) in the fluorescing compounds. Fluorescing compoundstypically have a chemical structure with alternating double bonds(including aromatics). Petroleum hydrocarbon fluoresces, and theresponse varies with the specific petroleum composition. It isunderstood that in various implementations, the response can becharacterized by the quantity and characteristics of light emitted, suchas by measuring red, green and blue (“RGB”) emissions and their relativeabundance.

According to another embodiment, a camera utilizing visible lightphotography can be positioned in the well casing 10 to perform aqualitative assessment of the geologic formation. This can be donequalitatively to determine the order of magnitude of the soil type(based on particle size) or more quantitatively by standard methods (todetermine particle size distribution based on digital imaging). Althoughit is customary for geologists to record detailed boring logs (includingparticle size at discrete intervals) after core collection (either inthe field or in the lab), such records can be lost or might beinconsistent. The use of the well casing embodiments disclosed orcontemplated herein enables reviewing this information at any time in anon-destructive way.

As mentioned above, according to one embodiment, the oil sensing device14 positioned in the well casing 10 can be a LIF probe (which includesthe UV light source 13). LIF uses a pulsed UV laser to inducefluorescence. Typically the fluorescence signal is separated in threechannels (one for each primary color). Hydrocarbons produce acharacteristic fluorescence pattern (combination of primary colors),based on hydrocarbon composition. FIG. 5 shows the results of a LIFprofile in contaminated soil. This example can be found online atwww.columbiatechnologies.com/membrane-interface-probe.

As also discussed above, in accordance with another implementation, theoil sensing device 14 positioned in the well casing 10 can be a cameraand a UV light source 13. As an example, FIG. 1 is a digital picture ofa sand tank experiment using a combination of natural (visible) and UVlight. The hydrocarbon was spiked with a fluorescent dye to enhance itsfluorescence. However, other experiments show hydrocarbon can generatehigh quality images without the fluorescent dye (the sensitivity of UVphotography with respect to LIF to low hydrocarbon saturations has notbeen tested, although it might be lower).

For the purposes of estimating LNAPL saturations in soils usingfluorescence, the digital pictures can be evaluated qualitatively or byusing digital imaging binarization techniques to quantitativelydetermine petroleum saturations. FIG. 6 shows the results of thistechnique.

In FIG. 6, the original digital image (left) is adjusted to binarize it(white pixels indicate fluorescence and NAPL presence, while black onesreflect the lack of it). The binary picture (center) is processed byaveraging values across each elevation (values of 1 for white, 0 forblack), determining average NAPL saturations at each elevation (right).

Although FIG. 6 was obtained from the outside of a sand tank experiment,use of a smaller camera with a short focal distance would enable takingsuch pictures from within a UV transparent well (as was the case forFIG. 11A). Off-the-shelf dental cameras have such capabilities(including deeming visible and UV lights separately), although thesecould be enhanced by providing supplemental light sources (either UV orvisible).

As also mentioned above, according to one embodiment, the oil sensingdevice (not shown) positioned in the well casing 10 can be a probecoupled to a spectrometer. Fluorescence can be measured with standardspectrometers. As the location of the fluorescent compound is remote, aprobe with fiber optics can be used to send excited light and signal.According to one embodiment, at least two types of probes can be used.One type is a probe in which the same light channel is used for theexciting incident light (UV) and the fluorescent signal. This mightrequire timing of the signal measurement, as UV light can generate anoisy signal that interferes with the wavelength of the fluorescence.After excitation, fluorescence lasts in the order of 10-09 to 10-07 s(http://chemistry.rutgers.edu/grad/chem585/lecture2.html). Someapplications of fluorescence collect the signal with a small delay afterthe excitation to reduce the noise due to the exciting light. The secondtype is a probe with multiple channels, some for excitation and some forfluorescence measurement, which can address the noise generated by theexciting light.

FIG. 7 shows a schematic diagram for one such probe 40. Fiber optics(FO) with exciting UV light are shown as open circles 42, fluorescenceemission is conducted by the central FO 44 to the spectrometer formeasurement.

FIG. 8 shows the signal obtained from diesel in soils using aspectrometer with a fiber optic array consisting of 6 incident channels(from a UV light source) surrounding a single signal channel feedinginto a commercial spectrometer (Avantis).

FIG. 9 depicts an example showing a simulated oil spill in a sand tank50. The sand tank includes porous media (sand), and water, to simulategroundwater. The example also included a UV-transparent well 12, atraditional half well 12 next to the sand tank glass, and a tube to feedwater without wetting the sand. The sand tank was filled with sand asmedia 52, then water was added and allowed to equilibrate with the soilfor about 10 hours to simulate groundwater. At that point, a contaminant54 was added to simulate an oil spill.

This example used baby oil with added fluorescent dye as a modelcontaminant 54. Many contaminants (i.e., diesel or gasoline) fluorescenaturally. The (simulated) contaminant 54 shows up in these pics asbright yellow, and only does so when excited by UV light.

In this example, a simulated UV-transparent well 12, having a splitcasing 10, was inserted and set against the glass of the sand tank 50for reference, to illustrate what type of information is available topractitioners using conventional monitoring wells.

In this example, a small camera was used in combination with UV andvisible lights to observe the formation within the UV-transparent well12, and compare it to the observations through the fish tank glass.

In FIG. 10, reference arrows show the saturated contaminant (LNAPL) 52thickness in the example. Note that there is also a region of the soil(above the water table, a region known as the vadose zone, as discussedpreviously) where there is soil with low concentration of contaminant(called residual, when it will not drain further).

FIGS. 11A-11D depict further views of the example of FIGS. 9-10. Thatis, FIG. 11A depicts a close-up view of the interior of the well 12 madeup of individual pictures pasted together. In FIG. 11B, the image ofFIG. 11A has been binarized, that is, the image has been rendered as allwhite or all black, using specific criteria to determine whatcombination of the primary colors in each pixel of the original digitalpicture determine the presence or absence of fluorescence (i.e.,contaminant). FIG. 11C depicts the saturation curve of the binarizedimage, showing the contaminant 54 saturation (the percent of pixelswhere there is fluorescence) at each elevation.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. As will be realized, theinvention is capable of modifications in various obvious aspects, allwithout departing from the spirit and scope of the present invention.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

Although the present invention has been described with reference topreferred embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

The invention claimed is:
 1. A method for measuring non-aqueous phaseliquids (“NAPLs”) comprising: emplacing a sealed well casing into amedia forming a dry well; inserting a sensing device and UV light sourceinto the sealed well casing; exciting fluorescence of NAPL with the UVlight source; capturing an image of the fluorescence; and processing theimage to quantitatively determine an amount of NAPL in the media.
 2. Themethod of claim 1, wherein no external materials are added around thesealed well casing while emplacing the well.
 3. The method of claim 1,further comprising freezing the media.
 4. The method of claim 1, whereinthe sensing device comprises a laser-induced fluorescence probe.
 5. Themethod of claim 1, further comprising identifying characteristics of theNAPLs via measuring red, green and blue emissions of the fluorescence.6. The method of claim 1, wherein the sensing device comprises a cameraand further comprising determining particle size of the media.
 7. Themethod of claim 1, wherein the processing comprises digital imagingbinarization.
 8. A system for detecting NAPL and petroleum comprising:(a) a UV transparent well casing; (b) an oil sensing device comprising acamera; (c) a display; and (d) a processor constructed and arranged toprocess signals from the sensing device to quantify the amount of NAPLin the media, wherein the display is constructed and arranged forvisualization of soil fluorescence and soil features, and wherein theprocessor is further constructed and arranged to determine average NAPLsaturations at various elevations.
 9. The system of claim 8, wherein theUV transparent well casing forms a dry well.
 10. The system of claim 9,wherein the oil sensing device further comprises a UV light source. 11.The system of claim 10, wherein the soil features visualized include atleast one of grain size and color.
 12. The system of claim 8, whereinthe oil sensing device further comprises a spectrometer.
 13. The systemof claim 12, wherein the oil sensing device further comprising a fiberoptic probe.
 14. The system of claim 8, wherein the UV transparent wellcomprises at least one of clear PVC, polymethyl pentene (PMP), UVtransparent acrylic, and glass.
 15. A kit for detecting non-aqueousphase liquid (NAPL) in a media comprising: (a) a UV light source; (b) asensing device; (c) a UV transparent well casing; and (d) a processorconstructed and arranged to process signals from the sensing device toquantify the amount of NAPL in the media, wherein the processor isfurther constructed and arranged to determine average NAPL saturationsat various elevations.
 16. The device of claim 15, wherein the sensingdevice further comprises a fiber optic device in communication with aspectrometer.
 17. The device of claim 15, wherein the sensing devicefurther comprises a digital camera.
 18. The device of claim 15, whereinthe sensing device further comprises a light induced fluorescence probe.19. The device of claim 15, wherein the processor is constructed andarranged to quantitatively determine NAPL saturations via digitalimaging binarization.